Fluid-pressure-engine-operated tool.



Gn H. GILMAN. FLUID massimi: ENGINE OPBMTED TOOL. APPLICATION FILEDSEPT, 5,1905.

Patented Got. 27, i908.

` improved pneumatic hammer.

Cir

` @mi 3 site GEORGE H. GILMAN, 0F CLAREMONT, NEW HAMPSHIRE,'ASSIGNOR TOSULLIVAN MACHINERY COMPANY, OF CLARE-MONT, NEW HAMPSHIRE, A CORPORATON0F MAINE.

no. ceases.

fpecleaten of Letteraluetefnt.

rammed oct. e7, isos.

Applicationfiied. September 5, Sosial Ho.. Sttten.

State of New Hampshire, have invented an Improvement inFluid-Pressaie-Engine-perated Tools, oi which the followingdescriptionpin connection with the accompanying drawings, is aspeciiication, like letters ont-he drawings representing like parts.

My invention relates to fluid pressure engines such as are operated bycompressed' air or other elastic fluid, being more particularlyconcerned with the provision of a new and My invention will be best iersto'od by reference to the following specn-..ation when taken inconnection with the aefoinpanying illustration of one speciiicembodiment thereof submitted for illustrative purposes, while .its scopewill he more particularly pointed out in the appended claims.

In the drawings,--- Figure 1 is a longitudinal central section talieiithrougzgh a pneumatic hammer embodying one yform of niy invention, thesection being taken on the irregular line l--l, indicated in liig. 3, inorder to show the various ports in one view; Fig. 2 is a similarsectional view, partially broken away, showing a niodilied `forni ofthrottle valve; Fig. 3 is a section through the valve-block taken on thelineS-S, Fig. l; Fig. 4 is a view of the inner end of the cylinder; Fig.5 is a section on the line 5-13, Fig. l g Fig. 6 is an end or top viewoi the valvei block cover; Fig. 7 is a similar view ol the valve-block;Fig. 8 is a section of the valveblocli on the line 8-8, Fig. l g Fig. 9is a similar section on the line Q -9, Fig. l and Fig. l0 is a sectionthrough the valve-block showing` the valve in its reverse position.

Referring to the drawings, the cylinder a is threaded into the hollowcasing 11, the valve-block c, which is provided with a valve cover d,actingr as a housingr or head for that end of the cylinder which isentered Within the casing. The cylinder, valve-block and coveraremaintained in the necessary alinenient required zfor the registrationof their connecting passages by means of dowel. pins (not shown).Slidably fitted over the head end oi the casinp isvtlie grasping handlee secured thereto and guided thereon by the hollow threaded stud f,which `asses through the slot e in the base of t e handle, the

1 sure maintained u i duct f3 until the tool is again grasped andpressed when c i the handle, being forced down upon the cashsndlethereby having ya limited movement toward and avvayfrrom the casing.

The head of the Vcasing is provideclwith ther constant pressure chamberg, to-which when the tool is in iiseair or other elastic luid isconstantly supplied ithrough the air inletf inthe hollow stud and thencethrough tl e hollow throttle valve fh and the passage' i.

For control of the air admission to the pressure chamber the hollowthrottle valve is provided with a plurality of admission 'ports h,registering with an annular groove f2, the latter connected to the.pressure inlet; The valve is provided also with a lurality of dischargeports 1c, registeringwit 'an arithe latter communicating nular groove t,with the passage i. When the operator withdraws the tool from the'workthe pressure of his hand against the grasping handle is relieved andluid pressure, w ich is constantly supplied from the pressure inletftothe interior of a hollow valve throuh the pressure duct fa forces thevalvebac Ward against the contacting face of the Agrasping handle andpushes the latter outward upon the casing. The valve follows'the handlein its movement until the latter is brought to rest against the stud f,this movement of the valve being su'icient to shut olf the ports h and7c from the grooves f2 supply of pressure to the engine. The prespon thevalve through the' holds the valve 1n its closed position against thework or other resistance,-

ing, moves the throttle valve to the open position shown.

The valve-block is oi a general cylindrical shape and has the interiorlyformed valve chamber c, within which is operatively secured the slidingpiston valve l, the valve chamber having the annular grooves m and n,separated by the li c2.

Live pressure is a mitted from the ccnstaiit pressure chamber g to thehead end of the cylinder, when the valve is in the position shown inFig. 1, through a series o mission ports o, extending longitudinallythrough the valve block cover and the valveblock as far as the lipv c2,necting the constant pressure chamber with the annular groove n. In theposition of the valve shown the barrel portion'Z thereof 1s and t andstop the and therefore coni immediately overt-he lip c2 'and the grooven llo is in free communication with the This permits the passage of fluifrom roove n to groove m and thence to the cylin er* through a series oflongitudinal ports p which connect the groove m with the ead end of thecylinder.

During the forward movement of the piston the piston valve'is held intheposition shown by the pressure in the constant pressure chamberacting upon the exposed end of the val/ve barrel and iiuid pressure isfreely admitted to the end ofthe cylinder, and, acting upon thepiston'ghead r, drives the same forward to deliver the blow u on thetool shank, the latter being held wit 1in they usual tool sleeve orbushing s.

During the forward movement of the piston the controlling valve isreversed by the admission of liuid ressure to the valve chamber underthe enlarged end Z2 thereof, this acting to raise the valve against thepressure upon the oppositeand smaller end and move it to the positionshown in Fig. 10. This valve reversing pressure is received throughlongitudinal intermittent pressure port t,

which opens into the valve chamber at t and .into the cylinder at t2 andalso at t3.

The intermittent pressure port is placed in communication wit i theconstant pressure port a opening into the cylinder at u and into theconstant pressure chamber through the valve block at u2 (Fig. 6) bymeans of a circumferential groove in the piston formed by the contractedpart r between the piston head and the main body portion r2. v"When thecircumferential groove uncovers the openings t2 and u', the intermittentpressure port t is placed in communication with the constant pressurechamber and the pressure therefore acts upon the enlarged end of thepiston valve to raise the -saine into the reverse position' shown inFig. 10.

ln the reverse osition of the valve the groove m in the va ve chamber iscut oil from the groove n by the flange Z3 upon the valve, and placed incommunication with the radial exhaust ports o. Through these the ressureat .the head end of the cylinder is ex austed into the chamber formedbetween the valveblock and the casing, and thence into the atmosphercthrough the two or more exhaust passages lvin the casing. At the sametime, the groove n and the valve admission ports` o are placei incommunication with the toolend, pressure port w, the latter entering thevalve cll amber at w and o ening into the cylinder at the forwardl en vthereof at w. W ith the reversal. of' the valve, therefore, pressure isadmitted from the constant pressure chamber through the tool-end,pressure port to the tool end of the-cylinder and acts upon the tool endof the pistonI to return the same as soon as the blow against the toolhasl been delivered andthe momentum of the piston overcome. The pistonhas theredraws the reducedytracted cylinder wa ls, placing the tool endduced portion r3, having a sliding fit Within the contracted Walls a ofthe cylinder, and the effective area against which the pressure acts inreturnin the piston is that of the shoulder formed etween the contractedor ytion r3 and the main body portion r2. lhis area is suliicient tocause the instantaneous return of the piston after its blow has been'delivered, lbut insuliicient materially to re'- duce the momentum beforethe blowis truck. On return movement of the piston under the pressureadmitted through the 'tool-end, pressure port w, the openings a andv t2are covered, and the opening t? uncovered. Fur# ther reverse movement ofthe piston withortion r from the conof the cylinder in" communicationwith the tool space a2 and the tool-end, exhaust passage This openscommunication between the atmos here and the intermittent pressure portt, tirough the opening t, and the fluid pressure 'within the valvechamber and back of therenlarged end of the valve being exhausted,thevalve is forced down to the position shown in Fig. 1. This againadmits pressure to the head end of the cylinder and cuts it off from thetool end thereof, the air at the tool end of the cylinder being eX-hausted through the exhaust opening The vreturn momentum of the pistonbeing overcome by the admission of air at the head end thereof, thepiston movement is reversed and it proceeds on its forward stroke asbefore y described.

To relieve the valve of any il uid pressure which might collect abovethe lip ll upon the piston valve and retard the lifting of the lat ter,the diameterof the valve-block and its cover is made slightly less thanthe diameter of the inclosing chamber, to form thereby a leak chamber.This is connected with rthe valve chamber by the groove yvand has freecommunication with the exhaust, thereby permitting the escape of anypressure which might retard the valve.

ln Fig. 2 I have shown a modified and vsimpler form of the throttlevalve shown in Fig.

l. In the construction of Fi f. 2 the parts arc substantially the sameas t iose shown in Fig. l, save that the interior of the hollow throttlevalve z opens directly into the constant pressure chamber, tho valvebeing provided with an enlarged head against the un 'ino der side ofwhich the valve-liliting pressure aets through the pressure duct e. l

The construction of the controlling valve for the engine described hasbeen .found in practice highly effective and` eflicient.A The employmentof a valve which-Works in a d1 125 rection opposite to that of thepiston while in alinement therewith, reduces the vibration imparted tolthe tool and the use of a piston valve provided with peripheralchambers through which pressure passes, as distingua Cri

eoasss guished Lrcrn e noliovf valve having radial ys,cendre to thegreater eihciency ci engine. lt ivili he.y observed that thetransmission of the huid pressure from the pressure chamber to thecylinder takes place with great-directrices through the longitulinalpassages in the valve-block and with out obstruction, thus avoidingdi'i'nson of the huid fessure in its entrance to the cylindes, whici isoften occasioned by its passage through circuitous ports.

l Yisle i have here illustrated and disclosed one embodiment ci myinvention for illustrative purposes, it is to be understood that thesame is not limited to the details, form, or relative arrangement ofparts disclosed, but that extensive modifications thereof may be medewithout departing from the spirit of my invention.

Claims i. A huid-pressure, direct-acting tool engine having a dierentialpiston valve normally maintained in one position 4by constant exposure oan area thereof to live pressure, a valve-block having 'an opening inwhich said valve is slidable one or more lonvitudinal passages in saidblock in addition to I said opening and connected with the pressuresupply, one or more longitudinal passages continuing through said blockbut longitudinaliy spaced from said @rst-mentioned longitudinal passagesand connected with the head end of the cylinder, said pressure passagesand cylinder passages being in communication when the valve is in normalposition, means controlled by forward piston 'movement for moving saidvalve to' cut off communication between said 2. A fluid-pressure,direct-acting tool engine a cylinder, a piston movable therein, a casingadapted to receive one end of said cylinder, a valve-block also withinsaid casing and adapted to act asa closure for the head end of saidcylinder, a valve block cover between said valve block and the casing,and a differential pressure piston valve having an area rexposed toconstant pressure and movable Within said valvelock in alinement withthe piston but oppositely movable therefrom said valve block having oneor more longitudinal passages therein in addition to the valve opening,and one or Yin ore longitudinal passages continuing through said blockbut spaced from said Erst-mentioned longitudinal passages.

A fluid pressure direct acting tool engine having a cylinder, a pistonmovable therein, a valve chamber separate' from the piston chamber and'located. at the rear end thereof, said valve chamber having a pair ofannular grooves, one or more longitudinal passages connecting one ofsaid grooves with the source of vpressure supply one or moreLingitudinal passages connecting the remainin groove with the head endof the cylinder,

(one orv more exhaust passages leaningxrom said vave chamber, a pressuresupplypasj' sage connecting said chamber with the tool end of thecylinder, and a piston valveadapt- .ed in one )osition to connect thepressure supply with the head end. of said cylinder through saidlongitudinal passages andfm another position to connect the pressuresupplyk with said tool end rassure supply pas sage through said iirstongitudinal passage or 'passages and the exhaust with the head end ofsaid cylinder through said second longitudinal passage or passages, saidvalve having an area exposed to constant pressure.

It. A fluid pressure direct acting tool engine having a cylinder,4apiston movable therein, a differential pressure piston valvecontrolling said pistonv and having an area exposed to constantpressure, a constant which said vaive operates and a pluraiity oflongitudinal passages connecting said valve chamber with said constantypressure chamber and connected with the valve intermediate the ends ofthe latter, communication between the engine cylinder and the severalpassages being simultaneously opened or closed by the valve.

5. A Huid-pressure, direct-acting tool engine having a cylinder, apiston, a differential pressure piston valve at the rear of said pistonhaving an area thereof constantly eX- posed to pressure, a valve chamberin which said valve operates, a constant pressure chamber, a pressurepassage leading from said valve chamber to the tool end of said piston,one or more straight-away longitudinal passages leading from saidconstant pressure chamber. to said valve chamber, one or morelongitudinal passages leading from said valve chamber to supply res sureto the head end of the cylinder, sai pas-v sages being longitudinallyspaced from said first-mentioned longitudinal passages, saidvalvebeing'adapted to connect valve chamber either with the head end of saidcylinder or With said tool end pressure supply passage.

6. A fluid-pressure, direct-acting tool-em gine having a piston valvehaving an area exposed to constant pressure, a valve-block providing achamber for said valve in alinement with the piston', said valve-blockbeing provided with two sets of straight-away longitudinal passagesspaced apart, one con necting the valve chamber intermediate the ends ofthc valve-With the head end of the cylinder and the other with thepressure supply.

7. A Huid-pressure, direct-acting tool engine comprising a cylinder, apiston, a diler ential pressure ,controllingl valve having its means foradmitting pressure to the large end ltliereof to reverse the valve onforward l movement of the piston, means on there- ,pressure chamber, avalve chamber Withinv smaller ond exposed to constant pressure,

CJi

scarce said valve chambergr'oove, a cylinder port comprising an annulargroove opening into the valve chamber in front of the inlet groovegrooveto the rearl of the cylinder chamber,

an exhaust port opening into the valve chamber ,in front of the cylindergroove and communicating at all times with the forward valve groove,Vsaid exhaust port being placed in communication with the cylindergroove on backward movement of the valve, and a second cylinder portconnected to the forward end of the cylinder chamber and having anopening into the valve chamber at the rear of the inlet port andconnected with the latter by the rear valve groove on backward movementof the valve.

:13. A fluid controlled impact tool having a cylinder chamber and apiston, a valve block having a valve chamber in alinement with and atthe rear or" the piston chamber, a reciproca-to differential pressureactuated valve slidab y mounted in the valve chamber and constantlypresenting a small differential pressure area to the motive fluid, saidvalve' being provided with two circumferential grooves, means forintermittently admitting pressure to the forward end of the valvechamber and against a larger difierential area of the valve, thereby toreciprocate the same, aninlet port opening'into the 'valve chamber andcomprising an annular inlet groove communicating at all times with therear groove of the valve, a plurality of longitudinal passagesindependent of the valve chamber connecting the inlet groove with alsource of fluid supply, a cylinder port opening into the valve chamberand comprising an annular groove in front of the inlet groove andcommunicating -with the said rear'groove of the valve on forwardmovement of the latter, a plurality of longitudinal passages alsoindependent of the valve lchamber and leading from the said cylindergroove to the rear of the cylinder chamber, an exhaust ort opening intothe valve charnber forwar( of the cylinder groove and cornmunicating atall times -with the forward groove of the valve, said Aexhaust portbeing placed in communication with the cylinder groove on backwardmovement of the valve, and a second cylinder port connected to theforward end oi' the cylinder chamber and having an opening into thevalve chamber at the rear of the inlet port and connected with thelatter by the rear valve groove o n back- Y ward movement of the valve.

14. 'A Huid controlled impact tool having es? ew reciprocatori*r.differential pressure actuated, valve slidabiy mounted in the valvechamber and constantly presenting a smaller `dilierential pressure areato the motive fluid, said valve being provided with two circumferentialgrooves, means for intermittently admitting pressure to the forward endof the valve chamber, and against a larger dierential area et the valvethereby to reciprocate the same, an inlet port opening into the valvechamber and communicating at all times with the rear groove of thevalve, one

or more longitudinal passages apart from the valve chamber connectingthe inlet port with the source of fluidv supply, a vcylinder portopening into the valve chamber'in front of the inlet port andcommunicating with the said rear groove ci the valve on forward movementof the latter, one .or more longi-` tudinal passages connecting thecylinder port with the rear ci the cylinder chamber, an exhaust portoening into the valve chamber in front of tie cylinder port andcommunicating therewith on' backward move ment of the valve, and asecond cylinder port connected to the forward end oi the c lind'erchamber and having an opening into tie valve chamber at the rear of theinlet port and opened to the latter bythe rear valve groove on backwardmovement ofthe valve.

15. an impact tool having acylinder chamber and a valve chamber inalinement therewith and atthe rear thereof, a difierential pressureactuated valve normally maintained in one position by constant en osn'reof an area thereof to live pressure, sai valve 'ill having twocircumferential grooves, an inlet ond cylinder port in the rear positionof the valve, and "t niet port and the iirst cylinder port in the rardposition of the valve, and the forward groove connecting the exhaustport and the iirst cylinder port in the rearward position, of the valve.v

lll. fin impact tool having a cylinder chamber and a valve chamber inalinement therewith and at one end thereof, a dii'erential pressureactuated valve normally maintained in one position by constant ex osureof an area thereof to live pressure sai( valve having twocircumferential grooves, an inlet ort constantly open to one groove, aneX- auat' port constantly open to the other 4 groove, a cylinder portbetween the' inlet and E on the opposite side'of the cylinder port fromexhaust ports and connected alternately with i the inlet port and openedthereto through the the said ports respectively by the saidcircumferential grooves, one or more longitudinal passages parallel withthe said valve chamber connecting the said inlet port and the source ofsuppl* one or more additional passages also para lel with the. valvechamber connecting the cylinder port with one end of the cylinderchamber, and a second cylinder port opening into the valve chamber A ,onthe oppositeside of the cylinder port from the iirst named cylinder portand connecting 'with the opposite end ci the cylinder chamber, thesecond cylinder port being placed in communication with the inlet portby the inlet groove vof the valve on each alternate movement thereof.

17. An impact' tool having a cylinder chamber and a valve chamber inalinement therewith and at the rear thereof, a difierential pressureactuated valve normally 1naintained in one position by constant exposureof an area thereof to live pressure, said valve havingV twocircumferential grooves, an inlet port constantly open to one groove, anexhaust port, a cylinder port between the inlet and exhaust ports andconnected alternately with the said ports respectively by the saidcircumferential grooves, one or more longitudinal vpassages connectingthe inlet port and the source of supply, one or more additionallongitudinal passages connecting the cylinder port with `one end of thecylinder chamber, and a second cylinder'port openin into the valvechamber on the opposite sit e of the inlet port `from the first cylinderport and connecting with the opposite end of the cylinder chamber, thesecond cylinder port being placed in communication with the inlet portby the inlet groove oi the valve on each alternate movement thereof.

18. A fluid controlled impact tool having a cylinder chamber piston, avalve block havving a valve chamber in alinement with the piston andatithe end of the piston chamber,

a reciprocatory dil'lerentia pressure actuated valve slidably mounted inthe valve chamber and constantly presenting a smaller dil'erentialpressure area to the motive fluid,

' said valve being provided with two circumferential grooves, means forintermittently admittin pressure to the valve chamber and against aarger differential area of the valve, an inlet port opening into thevalve chamber and communicating at all times with one groove of thevalve, one or more longitudinal passages apart from the valve chambercon necting the inlet port directly with a source of luid sup ly, acylinder port opening into the valve c amber and opened to thevinletgroove ofA the valve ,in one position of the latter, one yor morelongitudinal passages connecting the cylinder port directly with one endof the cylinder chamber, an exhaust port and at the end of the pistonchamber, a reciprocatory dilierential pressure actuatedl valve slidablymounted in the valve chamber and constantly presenting a smallerdiii'erential pressure area to the motive fluid, said valve beingprovided with two circumi'erential grooves, means for intermittentlyadmitting pressure to the valve chamber and against a largerdifferential areaoi the valve, an inlet port opening into the valvechamber and comprising an annular inlet groove communicatmg at all timeswith one groove of the valve, a plurality of longitudinal passages apartfrom the valve chamber connecting thednlet groove with a source of fluidsupply, a cylinder' port opening 1into the va ve chamber and comprisingan annular groove adapted to be placed in communication with the inletgroove of the valve in one position of the latter, a plurality of'longitudinal passages also independent of the valve chamber and leadingfrom the said groove to one end of the cylinder chamber, an exhaust portopening into the valve chamber on the. opposite side othe cylindergroove from the inlet groove and opened thereto through the remainingvalve groove, and a second cylinder port connectedwith the remaining endof the cylinder chamber and opening into the valve chamber on the oposite side of the inlet port from the first cy inder port.

K 20. An impact tool having a cylinder chamber, a valve blockarranged atthe `rear thereof and provided with a valve chamber in alinement with.the vpiston chamber, a difico -ferential pressure actuated valverhaving two circumferential grooves', an inlet port constantly open toone groove, an exhaust port, a cylinder port between the inlet andexhaust ports and connected alternately with the said ports respectivelyby the saidfgrooves', one or' more longitudinal, strai lit-away passagesformed in the valve bloc and leading from the inlet port to the adjacentend thereof, one or more similar assages leading from the cylinjder portto tile opposite end' of the valve block and connected with one end ofthe cylinder chamber, and a second cylinder port opening into the valvechamber on the op ositeside of the inlet port from the iirst cy inderport and connecting with the opposite end of the cylinder chamber.

21. An impact tool having a cylinder chamber, a valve block arranged atthe rear thereof and provided with a valve chamber alinement With thepiston cham-ber, apressure chamber formed at tne rear or the valve blockand connected with a source ci fluid supply, a differential pressureactuated valve inlet port, a cylinder port vbetween the inlet andexhaust ports comprising Aalso an annu-` lar groove, said cylinder ortbeing connected alternately with the said inlet and exhaust respectivelyby the said rear and forward grooves, a plurality of passages formed inthe valve block .and connecting the pressure cham-ber with the inletgroove, a plurality or' passages 'formed in the valve block andconnecting the cylinder groove with the rea-r end of the cylinderchamber, said passages ein tending in a general longitudinal directionand spaced one set from the other by the annular lip separating the twogrooves, and a second cylinder port opening into the valve chamber onthe opposite side of the inlet port from the irst cylinder port andconnecting with the forward end of the cylinder chamber,

22. An impact tool having a cylinder chamber, a valve vlolock at therear thereof `providing a valve chamber in alinementv with the cylinderchamber, a diierential pressure actuated valve presenting a smallerpressure area constantly exposed to the mo` tive duid thereby tomaintain the valve normally in one position, means `'or intermittentlyadmitting motive fluid to the forward end or" the valve chamber andagainst the larger pressure area of the valve, a constant pressurechamber formed at the rear of the valve block and to which niotlve iluidis constantly admitted, said valve chamber being provided vWith-a pairof annular grooves and with two sets of straight-away longitudinalpassages spaced apart by the annular lip separating the two grooves, oneset extend# ing through the valve block to the rear end thereof andhaving communication with the constant pressure chamber, and the other,set-

extending to the forward end thereof and havin communication with therear end of the oy mder chamber'.

23. An impact tool having a cylinder chamber, a valve block at the rearthereof providing a valve chamber-in alinement with the cylinderchamber, a differential pressure actuated valve presenting a smallerpressure area .constantly exposed to the motive fluid thereby tomaintain the valve normally in one position, n'reans for intermittentlyadinitting motive fluid to the Jforward end of tlie valve chamber andagainst the larger pressure area of the valve, a constant pressurechamber formed at the rear of the valve block and to which motive fluidis constantly admitted, said valve chamber being pro vided with an inletport and an adjacent i supply motive fluid to one end of t port openinglf" *I I ber, and with straighoaivay longitudinal p s sages spaced apartby the separation et the said ports, one passage extending the valvebloclr to the rear end thereof d communicating with the ant -pre rchamber, and the other enten the Ward end thereon and co;

the rear end ol the cylinder chamber.

24. ln an impact tool pistonchamber and piston, a valve block having'serein alinernent with the bore of the piston chaneber and provided withan inlet port to which the motive fluid is constantly admitted, anexhaust port in the valve -blcclr located lor- Ward of inlet port, valveprovidedwith. an annular groove which .is always opened to inn seatingsvn,

' said inlet port externally to the valve and an annular groove whichis, always opened to said exhaust port externally to *ne valve, a

cylinder port in the valve block located tor- Ward el the inlet port,one or more longitudinal passages formed in the valve block andconnecting the inlet port 'with the motive iluid in one or morelongitudinal passages also 'formed in the valve block andy connectingthe cylinder port with the rear end of the piston chamber. v

25. ln a fluid operated impact tool a valve bloclr provided with aninlet port and with ports communicating'respectively with opposite endsofthe cylinder adjacent to and on opposite sides of the inlet port andfurther provided with exhaust ports adjacent to the cylinder ports, avalve having an annular groove which is constantly open to said inletort and a pressure surface constantly subgect to fluid pressure tendingto press the valve in one direction and a larger pressure surface towhich the motive fluid is intermittently admitted to move the valve inthe opposite direction, the motive luid being supplied tlirough saidgroove alternately to opposite ends of the cylinder by thereciprocations of the valve, said valve having bearing surfaces oneither side of said groove which tend to prevent the motive fluid passinfrom the groove to the atmosphere and o such length that when the valveis in osition to lie cylinder the port leadingto the respective oppositeend of the cylinder is'in communication with: the adjacent exhaust port,one or more longitudinal passages formed in the valve blockandeonnecting the inlet port with the pres sure supply, and one or morelon itudinal passages a so formed in the valve b oel; and connecting theadjacent cylinder port with the adjacent end of the cylinder.

26. ln an impact tool a valve having an annular 'roove to which themotive fluid is constanty supplied and an simular groove which is alwayso en to the atmosphere -ei:- ternally to 'the va ve, a valve bloclhavingport communicating withfthe forward end ot iis ' therewith by thereciprocation of the valve communication therewith by said) wherebymotive fluid is supplied to and exhausted from the cylinder through saidport,

said valve block having. a port communicating with the rear end of thecylinder which is located between inlet andfexhaust orts in the valveblock and alternately aced in annular grooves in the valve, one or morelongitudi nal passages leading rearwardly from the inlet port to thesource of supply, and one or more longitudinal Vpassages "leading for--wardly fi-oni' the last named cylinder port and connecting with the rearend of the cylinder.

27. A. fluid controlled impact tool'having a cylinder chamber and apiston, avalve bloclr having a valve chamber in alinementI with and atthe rear of the .piston chamber, a pressure chamber formed ats-the rearof the valve block and 'tc which motive lluid is constantiy admittedfrom the source of su ply, said valve chamber being provided with ing tothe pressure chamber of reduced cross- Scctional area7 a reciprocatoryvalve leaving a portion of enlarged diameter slidably mounted in thevalve chamber and a Aortion of 'reduced diameter slidably fitting -t iesaid reduced opening and presenting to the con stant pressure in thepressure chamber a smaller differential area, the enlarged portion ofthe valve being provided with two circumferential grooves, meansforintermittently admitting pressure to the forward end of the valvechamber and against the larger dierential area thereof, an-inlet port'comprising an annular groove opening into the valve chamber andcommunicating With the rear groove of the valvein both positions of thelatter, a cylinder port comprising also an annular groove opening intothe valve chamber forward of the inlet port and communi-4 eating withthe said valve groove on the forward movement of the valve, an exhaust tport openin into the valve chamber in frontl of the cylin er port andplaced in communication Awith the-latter by the forward groove ofthevalve on the backward movement thereof, a' second cylinder portconnected with the forward end of the cylinder and opening into thevalve chamberat the rear i of the inlet port, and a second exhaust portopening into the valve chamber at the rear saidsecond cylinder portandseparated from the latter in the back position of thevalve by abearing surface intervening on the enlarged portion of the valve betweenthe rear groove and the reduced portion thereof, the said exhaust portbeing placed in com.- municatioii with the second' cylinder port bymeans of the reduced portion of the valve on forward movement of thelatter.

scenes tool having a cylinder chamber, a valve chamber and a constantpressure chamber at the rear of the valve i chamber, the lattercommunicating wlth the yconstant pressure chamber by an opening l ofreduced cross section, a valve having a portion of enlarged diameter atits forward endand a portion of reduced diameter at its rear end, thelatter slidably fitting the said reduced opening and presentingvto thecon.- stant pressure of the pressure'charnber a smaller differentialpressure area,said valve having two circumferential grooves, an inlet 128. An impactv passage connecting .the constant pressure chamber and theinlet port apart from the opening intothe valve chamber, an exhaust'port, a cylinder port betweenthe inlet and exhaust ports and connectedalternately with the said ports respectively by the said cirport on theopposite side of the inlet port from the lirst cylinder port andconnected with the opposite end of the cylinder chamf ber. i

'y 29. An impactl tool having a cylinder lchamber, a valve chamber and aconstant pressure chamber at the rear of the valve chamber, the lattercommunicating with the constant pressure chamber, an opening of reducedcross section, a valve having a portion of enlarged diameter at itsforward end. and a ortion of reduced diameter at its rear end, thelatter slidably fitting the reduced opening and presenting to theconstant pressure of the pressure chamber a smaller d1iferentialpressure area, a circumferential groove .same, a passage connecting theconstant ressure chamber and the inlet port apart rom the opening intothe yvalve chamber, a cylinder port adjacent the inlet port, and asecond cylinder )ort on the opposite side of the inlet port, t ie twocylinderfports being connecte alternately tothe inlet port by the groovein the valve.

and piston, a valve block havinga bore in alinement with the bore of thepiston chamber and provided with an inlet port to which 4constantpressure chamber locatedat the rear of the valve block, a bore ofreduced cross section leading from the valve chamber to the constantressure chamber', an exhaust port locate( forward of said inlet ort, avalve having a reduced portion sli ably fitting the said reduced boreand exposed to vthe pressure from the constantl pressure chamber,said'valve also having an annular groove which` is always open tosaidinlet port externally to the valve, andi'an annular groove open tothe' said exhaust port externally to the valve and a cylinder ort in thei valve block located forward of sai inlet port port constantly open tothe rezar groove, a-

30. In an impact tool a piston chamber1` the motive fluid isconstantly'admitted, a.

cumferential grooves, and a second'cylindcr in the valve, a portconstantly open to the grooves, an inlet port constantly open to onesure of the pressure chamber a smaller differential pressure area, aninlet port comprisin an annular groove, a plurality of longitudinepassages leading fromA said groove to the pressure chamber inde endentof the valve chamber opening, an af jacent cylinder port,

and a circumferential Groove the valve for connecting the cylindcer portand the inlet port..

32. An impact tool having a cylinder chamber and a valve chamber, avalve having a large pressure area at one end to which y pressure isintermittently admitted, said valve at the opposite end terminating in aportion of reduced diameter, a constant pressure chamber into which thevalve chamber opens and in which the opposite reduced end o the valve isexposed to constant pressure, said valve having two circumferentialgroove, an exhaust port, a cylinder port between the inlet and theexhaust orts and connected alternately with the sai ports respectivelyby the said I circumferential grooves, and a second cylinder port'opening into the valve chamber on the opposite side of the inlet rtfrom the first cyhnder port and connectin with the opposite end of thecylinder cham er, the second cylinder port being placed in communicationwith the inlet port by the inlet groove of the valve on each alternatemovement thereof.

33. A fluid controlled impact tool having a cylinder chamber and apiston, a valve block having a valve chamber in alinement with and atthe rear of the piston chamber, a pressure chamber formed at the rear ofthe valve block and to which motive fluid is constantly admitted, saidvalve chamber being provided with an opening of reduced cross sectionalarea to the pressure chamber, a reciprocatory valve having a portion ofenlarged diameter and a portion of reduced diameter the latterk slidablyfitting the said reduced openin and presenting to the constant ressure othe pressure chamber a smaller iflerential pressure area, the enlargedportion of the valve being provided with two circumferential grooves,means for intermittently admitting pressure to the forward end of thevalve, chamber and against the larger differential area thereof, aninlet port communicating at all times with the rear groove, a cylinderport in front of the inlet ort and communicating with the rear end o thecylinder said cylinderl ort being placed in communication with the inletport by the rear groove of the valve on forward movement of the latter,an exhaust port in front of the inlet port adapted to be opened to thecylinder port' by the remaining valve groove on backward movevment ofthe latter, and a second cylinder port at the rear of the inletortconnected to the forward end of the cy inder and opened to' the inletport by the rear valve groove on backward movement of the valve.

34. An impact tool having a cylinder chamber, a valve chamber and aconstant pressure chamber at the rear of the valve chamber, the latterconnected to the constant pressure chamber by an openingof rey ducedcross section, a valve having a portion of enlarged diameter at itsforward end and a portion of reduced diameter at its rear end,

the latter slidably mounted in the reduced i opening and presenting tothe constant pressure of the pressure chamber a smaller d1fier entialpressure area, an inlet port, an adjacent cylinder port, a longitudinalpassage leading directl from the inlet port to t e pressure cham erindependent of the valve chamber opening, and a lon itudinal passageleading directly from the cyiinder port to the cylinder.

35. An im act tool havingacylinder charnber, a valve block having avalve chamber at the rear of and in. alinement with the cylin-v derchamber, a valve having a larger pressure area at the forward endadjacent the cylinder chamber to which area pressure is intermittentlyadmitted, said valve at the rear end terminating in a portion of reduceddiameter, a constant pressure chamber formed at the rear of the valveblock in which the valve chamber o ens and in which the rear reduced endof t e valve is exposed to constant pressure, said valve having twocircumferential grooves, an inlet port constantly open to one groove, aninlet passage extending rearwardly from said groove through said valveblock, an exhaust port, a cylinder port between the inlet and exhaustorts and connected to the rear end of the cy inder chamber by passagesextending forwardly .from said port through said va ve block, and asecond cylinder port at the op osite side of the inlet port from saidfirst icy inder port and connected with the forward end of the cylinderchamber.

36. An impact tool having a cylinder chamber and a piston, a valve blockhaving a valve chamber in alinement with and at the rear of the pistonchamber, a valve having a larger pressure area at its forward end nextadjacent the cylinder to which ressure in intermittently admitted, saidva ve at its rear end terminating in a portion of reduced diameter, aconstant ressiire chamber into which the valve chanixb er opens and inwhich there 130 duced end of the valve is exposed to constant pressure,said valve having two circumferential grooves, an inlet port constantlyopen to one groove, one or more passages leading from the rear ofthevalve block to the inlet port, an exhaust port, a cylinder port betweenthe inlet and exhaust ports, one or more passages leading from thecylinder port to the front of the valve block and conmmunieating withthe rear of the cylinder, said cylinder port being connected alternatelywith the said inlet and exhaust ports respectively by the saidcircumferential grooves, and a second cylinder port opening into thevalve chamber on the Opposite side of the inlet port from the firstcylinder port a'nd alternate'ly o ened to the inlet port by the reargroove of the valve.

37 An impact tool havingacylinderchamber and a valve chamber inalinement therewith and at lthe rear thereof, a differential pressureactuated valve normally maintained' in one position by constant exposureof an area thereof to live pressure, said valve having twocircumferential grooves, an inlet port constantly open to the reargroove, an exhaust port in front of the inlet port, a cylinder portbetween the inlet and exhaust ports,

a longitudinal passage extending from theV cylin er port rearwardly tothe source of supply, a second lonvitudinal passage extending orwardlyfrom the cylinder port to the rear of the cylinder chamber, a secondcylinder port at the rear of the inlet ort and connected. with theforward end of t e cylinder chamber, and an exhaustv port opening intothe valve chamber at the rear of said -second cylinder port andclosed tosaid port in the rearward position of the valve by a bearing surfacethereof'but openedv thereto on forward movement of the valve.

38. An impacttool having aeylinder charnber and a valve chamberinalinement therel with and at one end thereof, a differential pressureactuated valve normally maintained in one position by constant exposureof an area thereof t0 live pressure, said valve having twocircumferential grooves, an inlet port constantly open to one groove, anexhaust port, a cylinder ort between the inlet'and exhaust ports an(connected alternately with the said ports respectively by the saidcircumferential grooves, a second cylinder port opening into the valvechamber on the op oslte side of the inlet port from the first cy inderport, said second cylinder port being laced in communication with theinlet port by the inlet groove of the valve on each alter- GEORGE H.GILMAN Witnesses:

GEO. S. BURRILL, MORRIS P. HOLMES.

